Endoluminal delivery of anesthesia

ABSTRACT

Described herein are methods and devices for selectively applying fluids (particularly anesthetics) to a target tissue from within a blood vessel while minimizing the amount of fluid applied to non-target tissue. The injection catheters described herein may include an elongate body, a directional injector, and one or more holdfasts for securing the catheter before extending the injector. The methods of selectively applying anesthetic to a target structure generally include the steps of inserting an injection catheter into a body vessel, positioning the injection catheter within the body vessel near the target structure, anchoring the injection catheter before extending a directional injector from the injection catheter, and applying anesthetic from the injection catheter to the target structure.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/282,222, entitled ENDOLUMINAL DELIVERY OF ANESTHESIA, filed Nov. 18,2005 now U.S. Pat. No. 7,879,011, which claims the benefit under 35U.S.C. §119(e) of the following U.S. Provisional Applications: (1) U.S.Provisional Patent Application Ser. No. 60/629,420, filed Nov. 18, 2004;and (2) U.S. Provisional Patent Application Ser. No. 60/664,142, filedMar. 21, 2005. Priority of the aforementioned filing dates is herebyclaimed, and the disclosures of the Applications are hereby incorporatedby reference in their entirety.

This application is also related to U.S. patent application Ser. No.10/996,301, filed Nov. 22, 2004, entitled, “Method and Apparatus forTreating a Carotid Artery” by David W. Chang, which is also incorporatedherein by reference in its entirety.

FIELD

The devices, systems and methods described here are in the field ofpercutaneous surgery, and particularly the area of anesthetic deliveryto specific tissue regions to assist with angioplasty or tissueablation.

BACKGROUND

Minimally invasive surgeries (e.g., percutaneous surgeries) account foran increasing number of medical procedures. These surgeries may resultin less patient trauma and may yield a significant cost savings as aresult of shorter hospitalization times and reduced therapyrequirements. Percutaneous procedures include endoscopic andcatheter-based procedures such as angioplasty (e.g., balloonangioplasty), stent delivery, and tissue ablation. In many of theseprocedures, pain, and even tissue damage, can be reduced or eliminatedby targeting delivery of anesthesia to the nerves or other tissuesadjacent to the vessel in which the procedure is taking place.

Examples of two treatments that could benefit from the controlledapplication of anesthetic to specific tissues include angioplasty andtissue ablation. For example, carotid angioplasty and stenting canresult in stimulation of the carotid sinus nerve, which can lead tobradycardia and hypotension, since acutely stretching or manipulatingthe carotid artery (which commonly occurs during angioplasty of thisregion) impinges on the sinus nerve. This can cause profound bradycardiaor asystole, leading to severe drop in blood pressure. Patients withsevere coronary artery disease or aortic stenosis may suffer cardiacarrest with hypotension. Stent placement can also cause prolongeddistention of the carotid artery resulting in continuous stimulation ofthe carotid sinus nerve, and may require treatment with vasopressormedications requiring observation in an intensive care setting.

Similarly, the treatment of tissue within a vessel by ablation (e.g.,using an ablation catheter), may deleteriously effect nearby tissuestructures. Ablation of tissue from within the vessel lumen heats evennon-target, e.g., adjacent tissue due thermal diffusion from theapplication of energy (e.g., electrical energy). This heat may causepain or trauma. The use anesthesia, particularly tumescent anesthesia,is one method of reducing the negative effects of endoluminal ablation.Tumescent anesthesia typically involves providing local anesthesia to asurgical site using dilute local anesthetic solution to both numb and“inflate” the tissue around the target ablation zone. Historically, thedelivery of anesthetic in tumescent anesthesia is accomplished bypercutaneous introduction of the anesthetic with a hypodermic needle(e.g., see U.S. Pat. No. 6,258,084 to Goldman, et al., hereinincorporated by reference in its entirety). This method is timeconsuming and requires repeated puncture of the skin if a significantsurface area must be treated. Moreover, direct targeting of thestructures to be rendered anesthetic may be diffuse and inaccurate,resulting in higher volumes and dose of anesthetic. Ideally, thetumescent anesthesia method would apply fluid (including fluid withanesthesia) to the perivesicular (or periluminal) region immediatelysurrounding the vessel in which the ablation catheter is positioned. Inparticular, the region around the blood vessel (e.g., between theendothelium and the subendothelial connective tissue) may be selectivelyinjected with a solution of anesthetic to optimize the effectiveness oftumescent anesthesia.

Although many medical procedures (including angioplasty and tissueablation as described) may benefit from the precisely controlledapplication of anesthetics, most practitioners continue to applyanesthesia with only limited specificity. Even when performingcatheter-based minimally invasive surgery, may practitioners applyanesthesia either systemically (e.g., applying it to the entire patient)or by injecting the anesthesia into the appropriate body region using aneedle. However, such percutaneous puncture results in difficult andimprecise deliver of anesthetic. This may also lead to injury ofadjacent structures including the veins, arteries, nerves, musculature,etc. Furthermore, imprecise injection can also result in dislodgingplaque, leading to thrombosis or other complications. These problems maybe avoided by the precise delivery of anesthetic from within the lumenof a vessel.

Unfortunately, most devices for releasing drugs from within the lumen ofa body vessel that are currently known, including most injectioncatheters and infusion catheters, suffer from various inadequacies thatmake them less than optimal for the precise delivery of anesthesia todifferent body regions. For example U.S. Pat. No. 6,210,392 to Vigil etal. describes an injection catheter for injecting fluid into a treatmentarea of a vessel wall. Similarly, U.S. Pat. No. 6,685,648 to Flaherty etal. describes a system and method for delivering drugs using a catheterhaving a deployable puncturing element. Other examples of injectioncatheters can be found in U.S. Pat. No. 6,458,098, U.S. Pat. No.6,692,466, U.S. Pat. No. 5,354,279, U.S. Pat. No. 6,302,870, and U.S.Pat. No. 5,693,029. Each of the above-mentioned patents is hereinincorporated by reference in its entirety.

Many of the injection catheters described in these patents do not allowprecise control of the stability of the catheter and/or the injector,and therefore may have problems controlling the amount and location ofmaterial (particularly anesthetic) applied. Stability of the injectioncatheter is particularly important when it is desirable to apply a fluid(e.g., a fluid containing an anesthetic) to a precise location outsideof the vessel lumen. Movement of the catheter caused by deploying theinjection port may prevent proper delivery of the fluid, and may lead todamage of the vessel or extravesicular structures. This may beparticularly true when the wall of the vessel is difficult to penetrate(e.g., because of plaque such as arterial plaques, etc.), or isirregularly shaped. Precise delivery of fluid allows for the selectiveuse of normal tissue planes (e. as channels for distribution of thefluid, further enhancing the specificity and decreasing damage to thetissue.

Thus, there is a need for methods and devices for delivering fluidsand/or anesthetics to precise locations adjacent to a body vessel fromwithin the vessel. The devices, methods and systems described hereinaddress this need, and the problems described above.

SUMMARY

Described herein are methods and devices for selectively and preciselyapplying fluid (particularly fluid containing anesthetics) to a targettissue from within a body vessel without substantially applyinganesthetic to non-target structures. These methods and devices may beused to deliver anesthetic at precise locations even within activevessels (e.g., blood vessels) and even when the dimensions of the vesselare unknown, or the wall of the vessel is occluded or congested.

In one variation of the method of selectively applying anesthetic to atarget structure, the method selectively applies anesthetic from withina body vessel without substantially applying anesthetic to non-targetstructures. In general, the method includes the steps of inserting aninjection catheter into a body vessel (wherein the injection cathetercomprises a directional injector configured to apply anestheticselectively to the target structure), positioning the injection catheterwithin the body vessel near the target structure, anchoring theinjection catheter before extending the directional injector toselectively deliver anesthetic to the target structure, and selectivelyapplying anesthetic from the injection catheter to the target structure.Any appropriate injection catheter may be used as part of this method,particularly injection catheters capable of directional application offluid as described herein.

The method of selectively applying anesthetic to a target structure mayalso include visualizing the injection catheter. For example, theinjection catheter may be visualized by fluoroscopic visualization,ultrasound, or any other technique or combination of techniques. Theinjection catheter or portions of the injection catheter (e.g., theextendable directional injector) may be marked so that it can be readilyvisualized. In some variations, the application of anesthetic to thetarget structure can be visualized (e.g., by including a maker orcontrast agent that is readily visualized by an appropriatevisualization method). For example, the marker or contrast agent (suchas a radiopaque material) may be added to the anesthetic when it isreleased to monitor how effectively the anesthetic is applied to thetarget structure.

The injection catheter may be inserted through any appropriate openinginto a body vessel. The injection catheter may be used as part of anypercutaneous procedure. For example, the injection catheter may beinserted from an incision in the femoral vein of the groin or through atranscervical incision. Although the body vessels described herein aremostly blood vessels (e.g., veins and arteries), the methods and devicedescribed herein may be applied to any appropriate body vessel,including non-blood vessels (e.g., urinary tracts, lymphatic vessels,etc.).

The injection catheter may be positioned within the body vessel near thetarget structure so that the injection catheter can access the targetstructure from within the lumen of the vessel by extending the injector.Positioning may include orienting the catheter. For example, theinjection catheter may be advanced within the vessel, withdrawn down thevessel, rotated within the vessel, or moved laterally within the vessel.In some variations, the injection catheter used is adapted to allow theentire catheter, or a region of the catheter, to be manipulated toposition the injector so that it can reach the target structure.Visualization of the catheter and/or the region surrounding the catheter(including the target structure) may be used to help position theinjection catheter, as described above.

Typically, the injection catheter is positioned before it is anchored.However, in some variations, the injection catheter may be onlyapproximately anchored, and then the position of the injector portion ofthe catheter may be adjusted to precisely orient the injector. In thesevariations, the injector portion includes a region that is adjustable tochange the location or orientation of the injector even when the rest ofthe injection catheter is secured in place. For example, the injectormay be rotated or moved (e.g., forward/backwards) with respect to theanchored injection catheter. The injector may also be independentlyextendable from the injection catheter, as described below. In somevariations, the injector and/or regions of the injection catheter thatallow modification of the orientation of the injector can be modified,secured or locked into position.

In general, the injection catheter is anchored before extending thedirectional injector to selectively deliver anesthetic to the targetstructure. Anchoring the injection catheter may prevent unwantedmovement of the injection catheter and therefore the injector. Movementof the injection catheter and resultant movement of the injector maychange the position of the injector with respect to the targetstructure, or it may even damage the target structure. The methods anddevices described herein allow precise positioning of the injector andtherefore injection of anesthetic in very exacting locations such asbetween tissue fascia, or around the sheath of a nerve without impingingon the nerve. Anchoring may stabilize the injection catheter. Anchoringmay be particularly useful because force may be required to extend theinjector. For example, force may be required to penetrate the wall ofthe vessel (particularly if there are deposits such as plaque on thevessel) or adjacent structures. The anchored injection catheter maytherefore allow leverage for extending the injection catheter.

In some variations, the step of anchoring the injection catheterinvolves using one or more holdfasts to secure the injection catheter(particularly the region of the injection catheter from which thedirectional injector extends) within the vessel. A holdfast may be anyfeature that is configured to anchor at least a portion of the injectioncatheter to prevent it from moving or shifting orientation with respectto the vessel and any extraluminal structures adjacent to the vessel.For example, a holdfast may include a stiff member, a brace, aninflatable balloon, a suction port, an expandable scaffold, a magneticlock, etc. The holdfast may be deployed by a practitioner once theinjection catheter is in a desired position. For example, in onevariation, the injection catheter is anchored by inflating a balloonconnected to the injection catheter to secure the injection catheterwithin the body vessel. In another variation, the injection catheter isanchored by deploying a stiff member that couples with the injectioncatheter. For example, a stiff or stiffenable rod may be inserted into alumen of the injection catheter once it is in position. Thus, the stiffmember can secure the injection catheter in place, and provide a stablesupport or brace for the injector. Alternatively, the injection cathetermay be configured of (or include) a stiff material. Multiple anchors maybe used with a single injection catheter.

The injector may be extended from the body of the injection catheter bya practitioner. In some variations, the injector is contained within thebody of the injection catheter, and exits from a port on the side or theend of the injection catheter. This port may be closed until immediatelybefore extending the injector, or it may be an opening that is alwaysopen. Extension of the injector may be controlled (e.g., guided) bystructures in the injection catheter. For example, the injector may bekeyed to the shape of the port on the injector catheter to preventundesirable movement of the injector with respect to the injectioncatheter. For example, a portion of the injector may have across-sectional shape (e.g., triangular) that mates with a channel inthe injection catheter to prevent rotation. The injector may be manuallyextended or automatically extended. The injector and injection cathetermay also be structured to limit the distance and/or rate that theinjector extends. The step of extending the directional injector mayinclude monitoring the orientation of the directional injector so thatthe directional injector can be extended to apply fluid to the targetstructure.

Anesthetic may be applied from the injector in any appropriate fashion.The injector may be a directional injector, which may apply fluid(including fluid with anesthesia) in an appropriate direction. Examplesof directional injectors are described herein, but may include injectorsconfigured to apply fluid in directions that are off-axis from thedirection of extension of the injector into the target tissue, andinjectors configured to apply fluid in a planar fashion or with aminimum or maximum pressure. Also described are directional injectorsthat apply fluid in a direction that is opposite to the direction ofextension of the injector (e.g., in the proximal direction of theinjector). Generally, the step of applying fluids such as anesthetics(or solutions including anesthetics) may include applying pressuredistally to release anesthetic from the injector. The step of applyingmay mean specific application of the fluid into the target tissue orregion while substantially avoiding the application of fluid tonon-target regions. Any appropriate fluid can be used, including fluidswith anesthetics. Examples of anesthetics that may be used includeBenzocaine, Mepivacaine, Ropivacaine, Bupivacaine, Lidocaine,Prilocalne, Procaine, Chloroprocaine, etc.

The methods described herein may be used with any appropriate targetstructure or tissue region. For example, the target structure maycomprise a nerve, or a sheath around a nerve, to provide localanesthesia. In one variation, the target structure is the sinus nerveadjacent to the carotid artery.

One variation of the methods described herein is a method of selectivelyapplying anesthetic to a subject's sinus nerve from within the carotidartery. The method includes the steps of inserting an injection catheterinto the carotid artery (wherein the injection catheter comprises adirectional injector configured to apply anesthetic selectively to thesinus nerve), positioning the injection catheter within the carotidartery near the sinus nerve, anchoring the injection catheter beforeextending the directional injector to selectively deliver anesthetic tothe sinus nerve, and applying anesthetic from the injection catheter tothe sinus nerve.

Providing anesthetic to nerves is particularly useful duringintravascular procedures near the nerve. For example, during angioplastyprocedures, it may be useful to provide anesthetic to nearby nerves(such as the sinus nerve) before beginning the angioplasty procedure orselectively after the angioplasty procedure.

Also described herein is a method of selectively applying anesthetic toa target tissue from within a blood vessel while minimizing the amountof anesthetic applied to non-target tissue. This method includes thesteps of inserting an injection catheter into a blood vessel,positioning the injection catheter within the blood vessel adjacent tothe target tissue by visualizing the directional injector and the targettissue, and applying anesthetic from the injection catheter to thetarget structure. The injection may have a directional injectorconfigured to controllably release anesthetic, and a holdfast foranchoring the injection catheter within the blood vessel. Othervariations of the injection catheter are also described herein.

An injection catheter may be used to selectively inject material to atarget structure adjacent to a body vessel. The injection catheter maycomprise an elongate body having a distal and a proximal end, a holdfastnear the distal end for anchoring the injection catheter within a bodyvessel, and an extendable directional injector having a distal end and aproximal end, the directional injector extendable from the elongatebody, wherein the directional injector comprises a tissue-penetratingsection at the distal end and a fluid delivery section located proximalto the tissue-penetrating section. The fluid delivery section may beconfigured to deliver fluid in a direction that is different from thedirection of tissue penetration (including the direction opposite fromthe direction that the injector extends).

The injection catheter may also include markers for visualizing theextension of the extendable directional injector 621 (referring to FIG.6). The injection catheter may also be configured to limit or controlthe amount (or rate) that the injector is extended. In some variations,the injection catheter includes a fine adjustment region which allowsthe injector to be oriented even after anchoring the injection catheterwithin the vessel.

As mentioned, one or more holdfasts may be used with the injectioncatheter, or may be integral to (e.g., part of) the injection catheter.For example, the injection catheter may include one or more inflatableballoons. The holdfast may be positioned distally and/or proximally tothe port from which the injector exits the injection catheter, or theymay be at the same axial position as the port along the injectioncatheter length. In some variations, the holdfast comprises a rigid orstiff member (or a member than may be rigidifiable), a brace, aninflatable balloon, a suction port, an expandable scaffold, a magneticlock, etc. The holdfast is deployable so that the injection catheter isallowed to move within the vessel when the holdfast is not engaged, butonce the holdfast is engaged it substantially prevents movement of theinjection catheter within the vessel.

Any appropriate injector may be used. Most injectors include one or morepenetrating sections for penetrating the wall of the vessel and anyother structures between the injection catheter and the target tissue.The penetrating section of the injector may be sharp or substantiallydull. In some variations, the penetration section comprises a bevelededge. An injector may also include one or more openings for passingfluid out of the injector into the tissue from a fluid delivery section.For example, the injector may have a fluid delivery section comprisingan opening that is in fluid connection with a lumen passing through atleast a portion of the directional injector. The fluid delivery sectionmay be configured so that the fluid is released in a desired manner(e.g., from a desired direction, or in a pattern such as a sheet orspray.

Also described herein are methods of selectively applying fluid fromwithin a blood vessel into the perivesicular space to create tumescence.These methods may include inserting an injection catheter into a bloodvessel (wherein the injection catheter has an extendable directionalinjector configured to controllably release fluid), positioning theinjection catheter within the blood vessel by visualizing thedirectional injector, extending the directional injector to pierce thevessel wall, and controllably applying fluid from the injection catheterto the perivesicular space. The fluid injected to create tumescence mayinclude an anesthetic (e.g., “tumescent anesthesia”).

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D illustrate one variation of the methods and devicesdescribed herein.

FIG. 1E shows an enlarged view of one portion of FIG. 1D.

FIGS. 2A-2E show different variations of the injection catheter asdescribed herein.

FIGS. 3A-3E show cross-sectional views of different variations of theinjectors described herein.

FIGS. 4A-4C show views of different injectors as described herein.

FIGS. 5A-5B show one variation of a method for selectively applyinganesthetic to a target tissue.

FIGS. 6A, 6B and 6C illustrate one variation of a method for creatingtumescence from an injection site within a vessel, as described herein.

DETAILED DESCRIPTION

Described herein are methods and devices for selectively applying fluids(particularly anesthetics) to a target tissue from within a blood vesselwhile minimizing the amount of fluid applied to non-target tissue. Theinjection catheter devices (or components of these devices) maygenerally be used to perform the methods for selectively applying fluidsto target tissues.

The methods of selectively applying anesthetic to a target structuregenerally involve positioning the injection catheter (also referred toherein as simply a “catheter”) within the body vessel near the targetstructure, anchoring the injection catheter to stabilize it and toprovide support or leverage for an extendable injector, then extendingthe injector and applying a fluid from the injection catheter to thetarget structure.

The injection catheters described herein have an elongate body, adirectional injector, and a holdfast to secure the injection catheterwithin the vessel. The combination of these features results in a devicethat can selectively and precisely apply fluid to a target site outsideof the vessel lumen in which the injection catheter is positioned. Asdescribed more fully below, these injection catheters can remain stableeven when manipulating the injector to penetrate tissue between theinjection catheter and the target tissue. Furthermore, these injectioncatheters may control the way that fluid is applied near or on thetarget tissue to prevent damage to the target tissue or more proximaltissues.

Although many of the examples provided herein refer to the applicationof anesthetics or fluids containing anesthetics, any appropriate fluidmay be used, with or without anesthetics. For example, fluids may beinclude saline, or solutions containing drug or therapeutics (e.g.,proteins, enzymes, small molecules, antibody-based therapeutics,nucleotide-based therapeutics, etc.). When anesthetics are used, anyappropriate anesthetic may be used, including Benzocaine, Mepivacaine,Ropivacaine, Bupivacaine, Lidocaine, Prilocalne, Procaine,Chloroprocaine, etc.

Methods

As described above, the method of selectively applying fluid to a targetstructure selectively delivers fluid from an injection catheter within abody vessel to the target tissue without substantially applying fluid tonon-target structures. This can be accomplished in four steps: (1)inserting an injection catheter into a body vessel, (2) positioning theinjection catheter within the body vessel near the target structure, (3)anchoring the injection catheter before extending the directionalinjector to selectively deliver fluid to the target structure, and (4)applying fluid from the injection catheter to the target structure. Anyappropriate injection catheters may be used, particularly the injectioncatheter described herein.

The injection catheter may be inserted into any appropriate opening intoa body vessel or lumen. For example, the injection catheter may beinserted as part of any percutaneous procedure (e.g., through thesubject's skin into the vasculature) so that the vessel is a bloodvessel (e.g., artery or vein), or into any other appropriate vessel inthe body. For example, the injection catheter may be inserted into alymph vessel, the intestinal tract, etc. Insertion and/or placement ofthe injection catheter may be manual (e.g., it may be advanced by hand),assisted, or automatically (e.g., robotically). The injection cathetermay be used with additional devices to assist in placement andpositioning. For example, insertion may involve the use of a sheath orguidewire. Thus, a flexible guidewire may be advanced to a location inthe body, and the injection catheter may be advanced along the guidewirethrough the body until it reaches the correct position.

One example of a surgical method that may benefit from the methods anddevices described herein is the TOPS method for treating a carotidartery, as described in the related U.S. patent application Ser. No.10/996,301, previously incorporated by reference in its entirety. Inthis example the catheter is inserted through a transcervical incisionand positioned within the carotid artery. As described more completelyin this application, the catheter may be used to shunt blood from theinternal carotid artery to a lower pressure reservoir, allowingtreatment of lesions in the carotid artery without distal embolization.The catheter used in this procedure may include an injector for applyinganesthesia (e.g., to the nearby sinus nerve), minimizing pain, risk, andpotential trauma from the TOPS procedure.

Once the injection catheter (or “catheter”) is inserted into the bodyvessel, it is advanced to a position in the body vessel adjacent or nearthe target tissue. At any time during the procedure one or more sensingtechniques may be used to assist the practitioner (e.g., doctor, nurse,etc.) in positioning and controlling the injection catheter. Forexample, the catheter may include one or more sensors (e.g., cameras,ultrasound transducers, etc.) on it to detect the position in thesubject's body, or to allow for an external device to locate thecatheter. The catheter and the subject's body may also (oralternatively) be visualized using any appropriate visualizationtechnique. For example, the subject's body may be visualized using afluoroscope, an ultrasound, etc. A “subject” may be anyone in need oftreatment, including medical patients. Subjects may include humans andanimals.

To aid in visualizing the position of the injection catheter within thesubject's body, any appropriate contrast agent or marker may be used.The contrast material may be matched to the type of imaging modalityused (e.g., radiopaque materials may be used, fluorescent dyes, etc.).In addition, fluid delivered by the injection catheter may also containa contrast agent or maker, to allow monitoring of the delivery of thefluid within the subject's body. For example, a contrast agent may beused with the anesthetic solution. Thus, the practitioner can confirmthat the material has been correctly applied. In some variations, asmall amount of fluid (even without anesthesia) may be applied toconfirm that the injection catheter has been correctly positioned.

The injection catheter should be positioned near the target structure sothat the injection catheter can access the target structure from withinthe lumen of the vessel by extending the injector. The step ofpositioning the injection catheter may include advancing, withdrawingand otherwise orienting the injection catheter. For example, theinjection catheter may be advanced within the vessel, withdrawn from thevessel, rotated within the vessel, or moved laterally within the vessel.In some variations, the injection catheter is manipulated by controllingthe proximal end of the injection catheter.

Manipulation of the injection catheter initially involves a “rough”positioning to place the catheter near the target site within thesubject's body. In some variations, once the catheter has been roughlypositioned within the proximity of the target tissue, it can be moreaccurately positioned by fine positioning after it has been secured intoposition within the vessel by a holdfast. Positioning the catheterwithin the vessel may also be done iteratively. For example, thecatheter may be positioned, secured into place with the holdfast, andthen unsecured and moved to reposition the catheter.

The step of positioning the catheter may mean positioning the injector(or injectors) of the injection catheter so that the injector can accessthe target tissue. For example, in variations of the injection catheterhaving an elongate injector that extends from an exit port or recess inthe body of the catheter, the catheter may be positioned so that theexit port for the injector is adjacent to the target tissue, allowingthe injector to be extended from the injection catheter and into thetarget tissue. In some variations of the injection catheter, the roughpositioning of the injection catheter is adequate for this purpose. Inother variations, the injection catheter may include a fine positioningregion (or an injector positioning region) that may be controllablymanipulated to allow limited positioning of the injector even after theinjection catheter has been secured into position by a holdfast.

An injector positioning region may be a region of the injection catheter(e.g., encompassing the exit port) that can controllably slide(proximally and/or distally) over a limited distance on the injectioncatheter, and may also rotate (e.g., around the circumference of theinjection catheter). The movement of this region may be controllable bythe user from the proximal end of the catheter. In some variations, theangle that the injector exits the injection catheter may be controlledto “aim” the tip of the injection within a set radius (e.g., withinabout ±20° from a direction normal to the long axis of the injectioncatheter). Aiming the injector in this way may be accomplished bychanging the position of the exit port with respect to the rest of theinjection catheter, and/or changing the angle of a deflection plate(described further below) which changes the trajectory of some types ofinjectors so that they may exit the injection catheter from a lumenwithin the injection catheter.

Once the injection catheter is at least roughly positioned, it isanchored or secured into position within the vessel, to preventsubstantial movement of the injection catheter with respect to thevessel. As described further in the section discussing injectioncatheters, any appropriate holdfast (or combination of holdfasts) may beused, including inflatable balloons, suction ports, braces, clamps,adhesives, rigid or rigidifiable members, expandable scaffolds, magneticlocks, etc. In essence, the holdfast should be prevent the catheter frommoving due to gross movements (e.g., flow of fluids within or around thecatheter, mechanical motion of the subject, etc.), potentially changingthe position of the injector with respect to the target tissue. Theholdfast may also prevent changes in the relative position of theinjector and the target tissue as fluid (e.g., anesthetic) is applied,since the application of fluid to the target tissue can result inlocalized swelling and distension of the tissue. In variations of theinjection catheter having a fine positioning control, an additional“lock” may be provide to secure the fine controls in a fixed positiononce the injector has been correctly positioned so that it can beextended to contact the target tissue.

The target tissue may be any appropriate tissue or body region asdescribed above. In particular, the target tissue is a tissue that islocated adjacent to a vessel which may receive the injection catheterand is within the extension range of the injector (particularly thefluid delivery section of the injector). For example, the target maycomprise a nerve, or a sheath around a nerve. In the variation descriedin Example 1, below, the target structure is the region surrounding thesinus nerve. In some variations, the target may be a tissue layer orfascia, such as the layers between vessels or other regions of bodyorgans. For example, it may be desirable to inject anestheticspecifically within such a layer before performing a surgical procedure(e.g., ablation) on the tissue or adjacent tissue.

The injection catheter is anchored before extending the injector becausethe movement of the injection catheter as it is being extended mayotherwise disrupt the position of the injection catheter as the injectorpushes against the tissue. This is particularly problematic whenextending the injection catheter into resilient tissues that resistpenetration, or tissues having plaques (e.g., atherosclerotic plaques).Anchoring the injection catheter into position within the vessel canprovide leverage so that the injector can apply force to penetrate thetissue and reach the target, without substantially changing the positionof the injection catheter. In some variations, the holdfast may itselfact as a support or brace for the injector.

The practitioner typically extends the injector from the body of theinjection catheter. In some variations, the injector is contained withinthe body of the injection catheter, and exits from an exit port on theside or the end of the injection catheter. The injector may be manuallyor automatically extended. The injector and injection catheter may alsobe structured to limit the distance and/or rate that the injectorextends. Once the injector is extended and positioned in, near, or onthe target tissue, fluid may be applied. In some variations, the fluidapplied is an anesthetic solution. Fluid is typically applied bysupplying pressure (e.g., from a syringe, pump, etc.) to the proximalend of the catheter, pushing fluid (which may be preloaded into theinjector before positioning) from the injector into the tissue. Theamount of pressure used to apply the fluid may be regulated at theproximal end, or the injector itself may include a structure (e.g., afilter, buffer, etc.) to limit the force which fluid exits the injector.

Any of the injectors described herein may be directional injectors, asdescribed further below. In general, a directional injector appliesfluid in a selected direction. For example, the directional injector mayapply fluid in a direction that is perpendicular to the direction ofextension of the injector or opposite the direction of extension of theapplicator. In some variations, the directional injector applies fluidfrom a fluid delivery section that is located on the side of theinjector. The injector may be adapted to apply fluid in a plane (e.g.parallel to the injection catheter).

FIG. 1 illustrates one variation of the method for selectively applyinganesthetic to a target structure. In FIG. 1A, an injection catheter 102is located within the lumen of a vessel 100. The walls of the vessel areirregular 104, 104′ (e.g., as might be found in an artery or othervessel). Adjacent to a portion of the vessel is a structure 106surrounded by a sheath 108. The injection catheter includes an injector110 which can exit the injection catheter from an exit port 112. Theinjection catheter also includes two holdfasts, here configured asinflatable balloons 114, 114′ on either side of the exit port 112 forthe injector 110.

In the transition between FIG. 1A and FIG. 1B, the injection catheter102 is positioned so that the exit port 112 for the injector 110 ispositioned near the target tissue 106, 108. In FIG. 1, the target tissueis area adjacent to the sheath 108, surrounding the structure 106. Forexample, the structure may be a nerve or nerve bundle (shown incross-section) surrounded by a nerve sheath. In some variations, thetarget may be the sheath 108 surrounding the structure 106. Thus, inFIG. 1B, the injection catheter has been positioned with respect totarget. The holdfasts (balloons 114, 114′) are then deployed, in thisexample by inflating them to secure the position of the injectioncatheter within the vessel, as shown in FIG. 1C. The holdfast balloonsprovide support against the uneven walls of the vessel 104, 104′ andprevent the vessel from moving. The balloon-type holdfasts shown in FIG.1 expand radially around the injection catheter, and therefore may serveto center at least this portion of the injection catheter within thecenter of the vessel lumen. The balloon (or other holdfast) may also beasymmetrically positioned, so that it preferentially secures theinjection catheter to one side of the vessel (e.g., maintaining theshortest distance between the injector and the target tissue). Althoughtwo holdfasts are shown in FIG. 1, it should be clear that no holdfastmay be used, or that only one holdfast may be used, although in somevariations more than one holdfast may be used (as shown). Furthermore,the position of the holdfast with respect to the exit port 112 for theinjector 110 may also vary. In some variations, the holdfast maysurround the exit port (and may include a passage for the injector). Insome variations the holdfast (or holdfasts) is located proximally ordistally to the exit port for the injector.

Once the injection catheter has been secured into position so that theexit port 112 for the injector 110 is located within reach of the targetwhen the injector 110 is extended, the injector may be extended throughthe vessel toward the target tissue or structure, as shown in FIG. 1D.The injector is extended from the injection catheter (through the exitport) until it penetrates the vessel and approaches the target 108. Thetip of the injector 122 is a tissue-penetrating region. In FIG. 1E, thistip is pointed, and has a relatively small gauge (e.g., greater than a22 gauge needle) so that it can readily penetrate the tissue. Proximalto the tip along the injector is the fluid delivery section of theinjector 120. The fluid delivery section is positioned near or in thetarget tissue 108, as shown in the enlarged view in FIG. 1E. Once thefluid delivery section of the injector 120 is properly positioned, fluid(e.g., anesthetic) may be injected.

In some variations, the target tissue is a layer or fascia of tissue ora region between structures. The injection catheter and directionalinjectors described herein may be used to specifically apply fluidbetween such tissue layers. Because the flow of fluid from the injectormay be specifically directed in a direction parallel with the tissuelayer (e.g., by matching the fluid delivery section of the injector withthe direction of the tissue layer, and/or by using injectors thatregulate the rate or force that fluid is applied).

Additional examples of the methods are provided below.

Injection Catheters

In general, the injection catheters described herein include an elongatebody, a directional injector that is extendable from the elongate bodyto penetrate tissue and deliver fluid in a direction that is differentfrom the direction of tissue penetration, and a holdfast for securingthe injection catheter within the vessel, providing support andstability to the injector.

The injection catheter typically has an elongate body with a distal anda proximal end. The body generally has one or more lumens along at leasta portion of its length (e.g., from the proximal end to at least theexit port for the injector. The body may include at least one passagethrough which one or more injectors are connected to a pressure or fluidsource. In some variations, the body includes additional passages, asfor a guidewire, endoscope, steering cable(s), or the like. The body maybe made of any appropriate material or materials, and may be flexible,jointed, stiffenable, or the like. The injection catheter may besteerable, as is known in the art. The injection catheter may be anyappropriate length. For example, the injection catheter may be many 3-6feet long (e.g., for percutaneous procedures entering through thefemoral artery for procedures on target tissues located more distally)or shorter (e.g., 4 inches to 3 feet for more proximal entry into thebody).

Injection catheters may also include one or more holdfasts, as describedbriefly above. A holdfast may be any structure for securing theinjection catheter within the vessel lumen. Preferably, the holdfastanchors the injection catheter within the injection lumen withoutdamaging the lumen or causing injury to the subject. In general, theholdfast may releasably attach or secure the catheter within the vessellumen. FIG. 2A shows some examples of different holdfasts that may beused with injection catheters. For example, in FIG. 2A, the holdfastcomprises a plurality of “feet” 204 that project from the body of theinjection catheter 202. These feet may be flexible (e.g., they may bemade of a spring-like material) so that they can expand to contact thewalls of the vessel when released from the body of the catheter. In theexample shown in FIG. 2A, the legs of the holdfast are ejected from thedistal end of the catheter, and expand outwards to contact the vessel asthe legs are extended. The ends of the feet may be configured so thatthey do not puncture or harm the vessel walls. For example, the feet maybe coated in a rubber or silicone. In some variations, the feet may becoated or treated with a material that readily adheres to the walls ofthe vessel.

FIG. 2B shows another example of a holdfast, comprising a stiff rod 208that locks the (otherwise flexible) catheter body into position, atleast over the region near the exit port 112 for an injector (notshown). The rigid rod may provide structural support for the injector asit is extended from the injection catheter. In some variations, theinjector is coupled to the body of the stiff rod 208, so that the rodprovides support for injector (and may steer the injector) as it isextended from the injection catheter.

The holdfast shown in FIG. 2C is a vacuum-type holdfast having twovacuum ports 220, 222′ that connect (via channels 224, 224′) to a vacuumsource. A vacuum may be applied through these ports so that when theinjection catheter is brought near the vessel wall, the injectioncatheter will suck onto the wall of the vessel and be held securely. Theamount of vacuum may be controlled to prevent damage to the walls of thevessel. Additional variations of the holdfast may be used as well(including the balloon-type holdfasts shown in FIG. 1). As previouslymentioned, the injection catheter may include multiple holdfasts whichmay be positioned in any appropriate way.

The injection catheter also includes one or more injectors, includingdirectional injectors, for injecting fluid (e.g., anesthetic) to atarget tissue. Injectors are extendable from the elongate body of theinjection catheter. In some variations, the injectors extend from theside of a distal portion of the injection catheter; however they mayalso extend from the distal end, or from more proximal locations. Theinjector typically comprises a tissue-penetrating section at the distalend of the injector and a fluid delivery section located proximal to thetissue-penetrating section. The fluid delivery section is configured todeliver fluid in a specific direction, or a selectable direction. Insome variations, the fluid delivery section is configured to deliverfluid from the injector in a direction that is different from thedirection of tissue penetration.

As previously mentioned, the injector may be manually or automaticallyextended (and/or retracted). In general, automatically extendedinjectors may include a trigger that releases the injectors from thebody of the catheter. Before it is released, the injector (or injectors)is protected from contacting and possibly damaging the vessel wall asthe catheter is positioned. After triggering the automatic release ofthe injector, at least the distal most tip of the injector is releasedfrom the body and extends from the exit port. For example, the injectormay be spring loaded so that it is released upon release of a structure(e.g., a sheath or cover) holding it in the catheter. In some variationsat least a portion of the injector is formed of (or connected to) ashape memory material (e.g., a nickel titanium alloy) that changes shapeto extend the injector.

FIGS. 2D-2E shows one variation of an injection catheter having anautomatically extending injector. As shown in FIG. 2D, the injector canbe kept within the body of the catheter and held secured by a cover 270.The cover has been removed (e.g., by sliding to the right), as shown inFIG. 2E, allowing the injector to be extended from the catheter. In somevariations, the injector may also be automatically or manually retractedafter it is deployed automatically, (e.g., and the cover 270 may bereplaced). In some variations, replacing the cover retracts theinjector. Any appropriate trigger may be used, and any appropriateautomatic extension may be used (e.g., springs, pneumatic extension,magnetic extension, etc.). The injector shown in FIGS. 2D-2E extendsfrom the body of the injection catheter in a predetermined angle that isnot perpendicular to the injection catheter, as shown. In general, theinjector may extend from the injection catheter body in any appropriatedirection.

In some variations using catheters having one or more automaticallyextending injectors, the catheter may be positioned, and the injector(or injectors) may be extended. When multiple injectors are used, thesame trigger may extend or allow all of the injectors to be extendedsimultaneously or individually. Once the injector is extended, it maythen be positioned against the vessel to allow penetration. Thisvariation (using multiple injectors for simultaneous penetration) may beparticularly useful when delivering fluid to the extraluminal spaceimmediately adjacent to the vessel.

The injector may be controlled to determine the direction and extent towhich it extends from the catheter. For example, the injection cathetermay include a guide, track, or channel (including a keyed channel, asdescribed previously) to control the direction of movement of theinjector. In some variations, the injection catheter comprises adeflection plate within the lumen of the catheter to direct the injector(as it is being extended) from the lumen of the catheter through theexit port in a continuous direction. In some variations, this deflectionplate can be adjusted to change the angle at which the injector extendsfrom the catheter body.

FIGS. 3A-3D show cross-sections of different variations of thetissue-penetrating section and fluid delivery section of directionalinjectors. For example, FIG. 3A shows the distal end of an injectorhaving a pointed tip 301. The injector contains a passage 302 throughwhich the fluid to be injected can pass. This passage 302 is connectedto the opening 304 of the fluid delivery section to allow fluid to bereleased. As shown in FIG. 3A, the fluid delivery section is located onthe angled portion of the tissue-penetrating section, and thereforefluid released from the injector may be released in a direction normalto the angled portion. In this variation, fluid is only released fromthis one exit of the fluid delivery section. FIG. 3B shows anotherexample in which fluid is released from the fluid delivery section intwo places 310, 310′. The directional injector maximizes the channelingof fluid along anatomical tissue and fascia planes, allowing themajority of the fluid to efficiently reach the target tissue, even whenthe target tissue is distant from the injector entry site, withouthaving to reposition the injector.

The direction that fluid exits the directional injector may bedetermined by the configuration of the fluid delivery section. Forexample, in some variations, the fluid delivery section releases thefluid in a direction that is opposite to the direction of extension ofthe injector (e.g., in the proximal direction of the injector). FIG. 3Eshows one variation of an injector in which fluid exits the injector inthe proximal direction (indicated by arrow). Another variation is shownin FIG. 5B.

The flow of fluid from the directional injector may also be regulated,as described above. For example, the directional injector may includebuffers, baffles or other structures to prevent fluid leaving theinjector from injuring the tissue. For example in FIG. 3C, the fluiddelivery section includes a filter 330 through which fluid must passbefore it can exit the injector. The internal lumen shape within theinjector 302 may also be configured to affect the flow rate anddirection of fluid leaving the injector. For example, the lumen mayinclude a widening of the passage to reduce the flow rate as the fluidleaves the injector.

The tissue penetrating region of the injector may be any shapeappropriate to penetrate the tissue, including sharp, beveled, pointed,rounded and dull shapes. For example, in FIG. 3D, the injector has abeveled shape. In general, the injector may have an overallneedle-shape, allowing it to readily penetrate the tissue. In theexamples shown in FIGS. 3A-D, the fluid delivery section is located onthe side of the tissue-penetrating section (and the tissue-penetratingsection and the fluid delivery section overlap). In some variations, theinjector may be a needle having a very small gauge (e.g., 20-30 gaugeneedle), and the fluid delivery section is located at the distal end ofthe injector.

FIGS. 4A-4C show additional views of injectors. In these examples, thefluid delivery section is located more proximally to thetissue-penetrating section. The fluid delivery section comprises exitsthat are shaped to regulate the flow and direction of fluid therefrom.For example, in FIG. 4A, fluid released from the fluid delivery sectionwould fan out in a plane that is perpendicular to the injector.Similarly, in FIG. 4B, fluid released from the fluid delivery sectionwould be ejected in a plane that is parallel to the injector. Thus, itis possible for the shape and orientation of the fluid delivery sectionto control the way that fluid is released.

In some variations, different injectors may be used with the sameinjection catheters. For example, the catheter may have an elongatechannel that extends proximally to hold an injector that can bewithdrawn and inserted (and extended) through the channel. Thus,injectors may be “swapped out” as needed with other injectors, based onthe geometry of the target tissue, or the relationship between thevessel and the target tissue. In some variations this may not bepossible, because the injector may be fixed within the injectioncatheter.

Described below are examples of the methods of using the injectioncatheters described herein.

Example 1

Surgical procedures (particularly percutaneous catheter-basedprocedures) may cause inappropriate nerve stimulation or even nervedamage. Anesthetizing only the nerve, or a sub-region of the nerve mayprevent pain, damage to the nerve, or damage to the patient than canresult from improper neural activity. For example, the carotid sinusnerve may be impinged during carotid angioplasty, stent delivery orother procedures performed in the carotid artery. This may causeprofound bradycardia or asystole. Clinical evidence suggests that inpatients undergoing carotid surgery (endarterectomy), direct applicationof anesthetic at the bifurcation can render the sinus nerve quiescent.

One variation of the methods described herein is a method of selectivelyapplying anesthetic to a subject's sinus nerve from within the carotidartery to prevent such problems. The method involves inserting aninjection catheter into the carotid artery, positioning the injectioncatheter within the carotid artery near the sinus nerve, anchoring theinjection catheter before extending the directional injector of theinjection catheter to selectively deliver anesthetic to the sinus nerve,and applying anesthetic from the injection catheter to the sinus nerve.

FIGS. 5A and 5B illustrate this method. In FIG. 5A, an injectioncatheter 501 has been positioned so that the exit port for the injector505 is adjacent to the carotid sinus 510. The injection catheter 501straddles the external carotid artery 512 and the common carotid artery514. The injection catheter 501 has been secured in the artery lumen bythe two holdfast balloons 507, 507′ attached to the injection catheter501, and the injector 505 has been advanced into the target tissue, thecarotid sinus 510. The distal end of an injector may be coated or filledwith a radiodense metal or resin to facilitate visualization of theneedle tip. Anesthesia may now be applied within the carotid sinus 510,as shown in the magnified view in FIG. 5B. This procedure may be done inconjunction with the TOPS procedure described briefly above, in whichthe flow of blood through the common carotid artery and the externalcarotid artery are arrested so that internal carotid artery backpressuresweeps dislodged debris into a lower pressure reservoir, allowing repairof lesions or other procedures. For example, in FIGS. 5A and 5B, theinternal carotid artery is shown having a buildup of stiff plaque 540.Removal of this plaque (e.g., by angioplasty, scraping, etc.) mayotherwise improperly stimulate or impinge on the sinus nerve. The methoddescribed herein may be used to apply anesthetic to reduce unwantedeffects.

Providing anesthetic to nerves such as the sinus nerve is particularlyuseful before performing intravascular procedures near the nerve. Forexample, during angioplasty procedures, it may be beneficial to provideanesthetic to nearby nerves (such as the sinus nerve) before beginningthe angioplasty procedure, while avoiding involvement with the recurrentlaryngeal nerve, phrenic nerve, superior laryngeal nerve, hypoglossalnerve, facial nerve, or vagus nerve. Indiscrete application ofanesthetic to these nerves can occur immediately or through diffusionfrom larger volumes of anesthetic delivered without directionalapplication. This may result in detrimental changes to speech,respiration, swallowing and facial expression, leading to poor subjectexperience, difficulty communicating, respiratory distress, andaspiration pneumonia.

Example 2

The devices and methods described herein may also be used to improvesurgical procedures on the vessels themselves. For example, fluid may beused to fill the space in the fascia around the vessel so that it swellsor becomes tumescent. This both narrows the vessel (making it easier toablate or operate on) and may separate the walls of the vessel that aresubject to the heat or pressure of the surgery from adjacent structuresthat may otherwise be injured. Tumescence is generally temporary, as thefluid is absorbed by the tissue over time. This procedure may bereferred to as tumescent anesthesia.

In typical tumescent anesthesia, a small needle (e.g., 27 to 30 gauge)is generally used from outside of the body to first numb the skin inmultiple locations, and then a larger needle (e.g., 19 to 25 gauge) isused to load the larger volume of tumescent fluid at an acceptable rateagain at multiple locations. However, this method is both inaccurate,time consuming, and potentially dangerous, as it risks injuring otherregions of tissue than the target region. In particular, when theprocedure to be followed involves operating on the walls of a vessel(e.g., by ablating with electrical energy), it would be much better toapply fluid beneath the fascia surrounding the vessel, so as to insulatenearly tissue structures. For example, tumescent anesthesia may behelpful when applying heat, laser, or electrical energy to ablateregions of a blood vessel wall.

In general, blood vessels follow the same histological makeup: the innerlining is the endothelium, followed by subendothelial connective tissue,and then a muscular layer of vascular smooth muscle. Finally, there is afurther layer of connective tissue (adventitia), which contains nervesthat supply the muscular layer, as well as nutrient capillaries in thelarger blood vessel. The blood vessel may be within a fascial layer.Thus, the methods described herein may be used to apply fluid (includingbut not limited to fluid containing anesthesia) to create tumescencebetween these layers (e.g., between the adventitia and the fasciallayer).

In this procedure, fluid is injected into the tissue from within theblood vessel, rather than external to the subject, avoiding the separatepunctures of the skin. The injection catheter may comprise any of thecatheters described above, and may have an injector with a delivery tubefor the anesthetic solution that is in the 21 to 30 gauge range forremote instillation of fluid into the extraluminal space. Furthermore,the region of the vessel made tumescent by the method described hereinmay be specific to the region that will be treated. In some variations,the injection catheter used to inject the solution causing tumescencemay include one or more ablation electrodes for treating the vessel.

Any appropriate amount of fluid used to create the tumescence may beadded, and this may be monitored by ultrasound. Generally, even thoughfluid enters the extraluminal space from a single insertion (e.g., asingle injector), the fluid may spread to surround the vessel, followingthe planes of the fascia in the space between the adventitia and thefascial layer (e.g., the subfascial layer). FIGS. 6A-C illustrates thismethod.

In FIG. 6A an injection catheter 601 has been positioned within a vein600, as described, and the holdfast (here consisting of two suction-typeholdfasts 603, 603′ surrounding the injector exit port 605) has securedthe injection catheter against the wall of the vein 600. The endothelium612 and subfascial layer 614 are also indicated. FIG. 6B shows amagnified view of the injector from FIG. 6A after it has been extendedinto the subfascial layer 614 (also shown in FIG. 6C), and has begunapplying fluid 625 (schematically illustrated by the speckled pattern).The fluid is released by the injector in a substantially proximaldirection with respect to the injector (as indicated by the arrows).Thus, the fluid 625 is released into the layer 614, and the force ofrelease of the fluid does not damage the tissue or impinge onneighboring layers. In addition, the layer will serve as a channel orguide for the fluid.

FIG. 6C shows the injector 620 after it has injected a substantialamount of fluid 625 into the subfascial layer 614, creating tumescencewhich has both reduced the diameter of the vessel 600, and has increasedthe distance between the outer wall of the vessel 612 and any nearbystructures. Once adequate tumescence has been established (as viewed byultrasound, for example), the injector can be withdrawn and the catheteradvanced to a nearby region if further tumescence of this vessel isdesired. The vessel can then be treated, e.g., by ablation orapplication of energy.

In this example, the structure is anesthetized by the addition of asolution containing anesthesia to create tumescence and it is localizedwith ultrasound guidance. As described above, the solution need notcontain anesthesia. Furthermore, although this example shows avacuum-type holdfast, any appropriate holdfast (or injector) may be usedas part of the injection catheter.

Without the methods described herein, the use of tumescent anesthesia isboth difficult and potentially dangerous. For example, in thin patients,the tumescent fluid must be applied just under the skin where it is hardto see the needle. In deep structures, the needle may not be easilyvisualized or multiple adjustments may be needed to the ultrasound probeorientation to align it with the needle and the structure to be treated.For example, the treatment of the short saphenous vein in the posteriorcalf currently requires the patient to be supine or in an awkward bentposition to allow sufficient space to place the ultrasound probe and toallow the operator to see the alignment of the needle to the ultrasoundprobe. Treatment in the supine position requires repositioning,repreparing and redraping of the patient to subsequently treat veins onthe anterior surface of the body.

The use of the methods and apparatuses described herein can also beapplied to procedures such as radiofrequency or laser ablation of venousstructures for varicose veins or chronic venous stasis. Both techniqueshave an incidence of parasthesias from injured nerves that run adjacentto the vein. Heat energy that is not effectively buffered by tumescentfluid may result in damage to subcutaneous and skin tissues. Inparticular, the increased incidence of post procedure bruising and painfrom treatment with the hotter laser catheter may be avoided usingendolumenal tumescent injection that more accurately deploys a greatervolume of tumescent fluid adjacent to the vein and avoids skipping areasresulting in poor tumescence.

Furthermore, the space from skin to the vessel created by the tumescentfluid layer decreases with time as fluid diffuses into the surroundingtissues. The direct application of fluid to the perivascular space aloneand the ability to easily instill fluid at the time of active ablationallow maximal separation of the heat source from nerve, skin andsubcutaneous tissue. The fluid can also be cooled down (e.g., to nearfreezing) to further reduce damage to surrounding tissues. The method ofendolumenal delivery of tumescent anesthesia can allow direct placementof fluid adjacent to the active heating element used for ablation, andthis fluid can absorb some of the heat energy before it has a chance toharm adjacent structures. This could be particularly useful for treatingthe short saphenous vein where the nerve courses more closely with thevessel. Currently, the most prudent approach used is to treat a shortsegment of the proximal vein where the nerve is generally more separatedfrom the vein. This method is less desirable than the method outlinedherein, because treatment of a short segment increases the risk offailed closure of the vein or reflux of blood from branches below thetreated vein. The techniques described above may enable safe treatmentof a longer length of vein, thereby improving results.

While the invention has been described in terms of particular variationsand illustrative figures, those of skill in the art will recognize thatthe invention is not limited to the variations or figures described. Inaddition, where methods and steps described above indicate certainevents occurring in certain order, those of skill in the art willrecognize that the ordering of certain steps may be modified and thatsuch modifications are in accordance with the variations of theinvention. Additionally, certain steps may be performed concurrently ina parallel when possible, as well as performed sequentially as describedabove. Therefore, to the extent there are variations of the inventionwhich are within the spirit of the disclosure or equivalent to theinventions found in the claims, it is the intent that this patent willcover those variations as well. Finally, all publications and patentapplications cited in this specification are herein incorporated byreference in their entirety as if each individual publication or patentapplication were specifically and individually put forth herein.

1. A method of applying anesthetic to a target structure from within abody vessel without substantially applying anesthetic to non-targetstructures, the method comprising: inserting an injection catheter intoa body vessel, wherein the injection catheter comprises a directionalinjector configured to apply anesthetic selectively to the targetstructure, wherein the target structure comprises the sinus nerve;positioning the injection catheter within the body vessel near thetarget structure; anchoring the injection catheter; extending thedirectional injector to deliver anesthetic to the target structure; andapplying anesthetic from the injection catheter to the target structure.2. The method of claim 1, further comprising the step of visualizing theinjection catheter.
 3. The method of claim 2, further comprisingvisualizing the injection catheter by fluoroscopic visualization.
 4. Themethod of claim 1, further comprising the step of visualizing theapplication of anesthetic to the target structure.
 5. The method ofclaim 4, wherein the step of visualizing the application of anestheticto the target structure comprises releasing radiopaque substance withthe anesthetic.
 6. The method of claim 1, wherein the step of anchoringthe injection catheter comprises inflating a balloon connected to theinjection catheter to secure the injection catheter within the bodyvessel.
 7. The method of claim 6, wherein the step of anchoring theinjection catheter comprises deploying a stiff member to which theinjection catheter couples.
 8. The method of claim 1, wherein the stepof extending the directional injector comprises monitoring theorientation of the directional injector so that the directional injectoris positioned near the target structure.
 9. A method of applyinganesthetic to a subject's sinus nerve from within the carotid artery,the method comprising: inserting an injection catheter into the carotidartery, wherein the injection catheter comprises a directional injectorconfigured to apply anesthetic selectively to the sinus nerve;positioning the injection catheter within the carotid artery near thesinus nerve; anchoring the injection catheter; extending the directionalinjector to selectively deliver anesthetic to the sinus nerve; andapplying anesthetic from the injection catheter to the sinus nerve. 10.A method of applying anesthetic to a target structure from within a bodyvessel without substantially applying anesthetic to non-targetstructures, the method comprising: inserting an injection catheter intoa body vessel, wherein the injection catheter comprises a directionalinjector configured to apply anesthetic selectively to the targetstructure positioning the injection catheter within the body vessel nearthe target structure; anchoring the injection catheter by inflating aballoon connected to the injection catheter to secure the injectioncatheter within the body vessel and deploying a stiff member to whichthe injection catheter couples; extending the directional injector todeliver anesthetic to the target structure; and applying anesthetic fromthe injection catheter to the target structure.